CSS Regression Testing

CSS regressions are visual. Your tests should be too.

UIProof screenshots your site after every deploy, diffs captures pixel-by-pixel, and uses AI to flag broken layouts, font changes, and spacing issues — without writing a single test.

Start free View live demo

Why CSS regressions are so hard to catch

CSS is global, cascading, and fragile. Traditional testing tools weren't built for visual problems — UIProof was.

CSS changes cascade unpredictably

A single class rename or Tailwind purge misconfiguration can break layouts across dozens of pages. UIProof catches every affected route — not just the one you edited.

Dependency updates shift styles silently

Bumping a UI library, updating Tailwind, or upgrading Next.js can introduce subtle spacing, font, or color changes. UIProof screenshots before and after so nothing slips through.

Refactors break what unit tests can't see

You can have 100% test coverage and still ship a broken layout. CSS regressions are visual — they need visual testing. UIProof fills the gap your test suite can't.

Multi-viewport regressions hide on desktop

A layout that looks fine at 1440px can be completely broken on mobile. UIProof tests desktop, tablet, and mobile on every capture — every time.

How CSS regression testing works

Five steps from zero to automated CSS regression detection — zero test code.

Add your routes

Enter your URLs. UIProof captures every page across desktop, tablet, and mobile — no browser extensions or test scripts needed.

Establish a baseline

UIProof takes pixel-perfect screenshots of your current state. This becomes your visual source of truth.

Ship your CSS changes

Refactor, update dependencies, or let AI agents generate code. Then trigger a new capture via dashboard or API.

AI classifies every diff

UIProof compares captures pixel-by-pixel. The AI layer classifies each change as cosmetic, intentional, or regression — with severity scoring.

Fix only what matters

Get alerted on real regressions. Ignore intentional changes. See exactly which routes, viewports, and elements were affected.

Visual CSS testing, fully automated

Screenshots, diffs, AI classification, alerts — one tool, no configuration.

Pixel-level diff across desktop, tablet, and mobile

AI classification: cosmetic vs. intentional vs. regression

Severity scoring: minor / review / regression

No test code — works against any live URL

Capture history: browse and compare any two snapshots

Email and webhook alerts on regressions

Public REST API for CI/CD integration

Persona-based UX scoring for conversion impact

Your test suite passes. Your layout is broken.

CSS regressions live in the gap between code correctness and visual correctness. A component can render the right HTML with the wrong styles. UIProof closes that gap — testing what your users actually see, across every viewport, after every deploy.

Pixel-perfect comparison

3 viewports per route

AI-powered classification

Frequently asked questions

How is UIProof different from snapshot testing in Jest or Storybook?

Snapshot tests compare serialized component output — they catch structural changes but miss visual ones like broken layouts, wrong colors, or spacing shifts. UIProof captures real browser screenshots of your live site and compares them visually. It catches the regressions that unit tests and snapshot tests structurally cannot.

Do I need to set up Playwright, Cypress, or Selenium?

No. UIProof handles all browser automation internally. You provide URLs — UIProof does the rest. No test infrastructure to maintain, no flaky browser drivers to debug.

Can UIProof detect font, color, and spacing regressions?

Yes. UIProof's pixel-level diff catches any visual change, no matter how subtle. The AI classification layer then determines whether a change is a real regression or an intentional update, and provides a plain-English explanation of what shifted.

How does the AI know the difference between a regression and an intentional change?

UIProof's AI model analyzes the visual diff alongside both captures. It considers context — a full-page layout shift after a CSS refactor is flagged differently than a deliberate color palette update. You get a classification (cosmetic / regression / intentional) and a confidence-scored explanation.

Can I integrate UIProof into my CI/CD pipeline?

Yes. UIProof provides a public REST API. You can trigger capture runs from GitHub Actions, Vercel deploy hooks, or any webhook-based pipeline. API keys are managed in your dashboard.

What frameworks does UIProof work with?

UIProof works with any web framework — Next.js, Nuxt, Remix, Astro, Rails, Laravel, plain HTML. It tests the live rendered page in a real browser, so it's framework-agnostic by design.

Stop shipping CSS regressions

Free plan. No credit card. No test code. Add your URL and UIProof catches what your test suite can't.

Start free — no credit card